I have used https://www.gumbigear.co.uk before and for work – good quality and price, know how to deal with re-sealing or not puncturing waterproofs etc.
They can also get some half decent clothes, although we have direct account with The Outdoors Company to get our Berghaus staff gear. markdix@theoutdoorscompany.co.uk
Most bigger outdoor manufacturers now won’t open trade account unless you are ordering £5k, GoOutdoors et al basically work on what they have in stock or Regatta. The only exception was Keela in Fife, but our staff vary from size 8/5′ to *ahem* much larger/6′ in womens – and only Berghaus could cope with that size difference, including varied legs of waterproof trousers.